The present invention relates to both a manufacturing apparatus for an organic electroluminescence display and a method of manufacturing an organic electroluminescence display.
An organic electroluminescence element is structured by an organic layer including an organic material sandwiched between electrodes made of an anode and a cathode. It is known that when voltage is applied across these electrodes, electrons and holes are injected from the cathode and anode into the organic layer of the organic electroluminescence element. These electrons and holes recombine to emit light.
In such an organic electroluminescence element, a luminescence of, for example, several hundreds to several tens of thousands of cd/m2 is obtained with a driving voltage of less than 10V. Further, the organic electroluminescence element can emit light having a suitable color by suitable selection of the luminous material, that is, the fluorescent material. Thus, a display using organic electroluminescence elements promises a multi-colored or full-colored display that may take the place of a cathode ray tube (CRT) display.
As the above described organic layer, an organic layer made of three to five stacked organic material layers such as a hole injection layer, a hole transfer layer, a light emitting layer, and an electric charge injection layer is known. Each of the organic material layers is formed by vapor deposition of the organic material in a processing chamber.
Each organic material layer may be vapor deposited in the same processing chamber. Specifically, vapor deposition includes aligning a mask arranged in a processing chamber and having openings corresponding to the pixels of a display with a substrate loaded into the processing chamber, inserting different vapor deposition materials in a number of heating vessels arranged in the processing chamber corresponding to the organic material layers, and heating these to cause the evaporation of the materials.
However, when forming an organic layer having a number of organic material layers in the same processing chamber, as described above, there are disadvantages in that a cycle time of the process for forming the organic layer can become extremely long. Thus, mass production of such a display using organic electroluminescence elements can be difficult.
When forming an organic layer having a number of organic material layers in the same processing chamber, it is necessary to heat each vapor deposition material for each vapor deposition. A relatively long time is needed until reaching the desired temperature and a relatively long time is needed until an evaporation rate of a vapor deposition source becomes stable. Thus, the waiting time before starting vapor deposition for each organic material layer is extended. As a result, it takes an extremely long time to form an organic layer.
Conversely, by heating the vapor deposition materials to a predetermined temperature at all times to stabilize the evaporation rate, it becomes possible to shorten the waiting time before starting the vapor deposition for each organic material layer. However, while vapor depositing an organic material layer corresponding to one vapor deposition source, vapor deposition materials are also evaporated from other vapor deposition sources. Thus, wasteful consumption of materials is hard to avoid. The organic materials used for an organic electroluminescence element are very costly, so the production cost of the organic layer swells and, as a result, the mass production of a display using organic electroluminescence elements becomes difficult.
A technique for eliminating some of the disadvantages caused by forming an organic layer in the same processing chamber is disclosed, for example, in Japanese Unexamined Patent Publication (Kokai) No. 8-111285.
The above publication discloses a technique of arranging processing chambers for vapor deposition of the different organic material layers around a vacuum chamber and transferring a substrate between the processing chambers through the vacuum chamber. By dispersing the vapor deposition of the organic material layers to different processing chambers, it becomes possible to greatly shorten the waiting time for heating the vapor deposition sources and stabilizing the evaporation rate.
However, if dispersing the vapor deposition of the organic material layers to different processing chambers, alignment work between the substrate and mask becomes necessary in each processing chamber. As a result, it is very difficult to sufficiently shorten the cycle time of the process for forming an organic layer. Further, during the alignment work, the vapor deposition materials can be wasted.